The present invention is in the field of digital photography and printing, and pertains more particularly to a method and apparatus for digital photography, and use of the photographic data for creating interference holograms using printing apparatus.
Rendering 3-dimensional (3-D) graphics on a 2-dimensional plane such as a computer monitor screen has been an emerging technology marked with many advances. For example, with the use of special 3-D cards and adapters, a 3-dimensional object may be created from dimensional information provided of the form of input to a computer system running appropriate software. After calculating input data, the computer system renders a simulated 3-D image on its 2-dimensional screen. A viewer may use special goggles to view 3-D images on a computer screen or other two-dimensional apparatus such as on a movie screen.
In another aspect of the art, hologram techniques are also used to produce 3-D effects on plastic cards and the like. Such holograms are familiar to many as embossed on such as credit cards. This sort of hologram is called a white-light-interference hologram, and is created through a reflective surface having a relatively complicated topology that reflects white light in a manner to produce interference patterns that the human eye sees as a 3-D image.
This technique is commonly practiced with the use of a stamping operation onto plastic surfaces, such as with holographic baseball cards and the like.
Unfortunately, 3-D image media such as white light holograms cannot be printed by conventional computer techniques or easily acquired. What is clearly needed is a method and apparatus that will allow 3-dimensional renderings of real photographed objects to be printed much the same as two-dimensional images are printed, using such as ink-jet technology. In the descriptions which follow a new collection and rendering technology is taught in enabling detail wherein, with the use of a computer station, an image may be captured with a digital camera and rendered by a special printer as white light interference hologram.
In a preferred embodiment of the present invention a system for producing a white-light interference hologram is provided, comprising a camera adapted for recording a first and a second bitmap image of a scene from separate vantage points, and the separation distance of the vantage points; a computing engine adapted to compute three-dimensional x, y, and z characteristics of an interference hologram topology for the scene from the bitmap image and separation data, wherein x and y are two dimensional locations of bits in a bitmap of the topology and z is a depth dimension for each x,y bit; and a printer adapted to print in color the x,y bitmap, and to create the depth dimension z at each x,y bit location, providing thereby a three-dimensional interference hologram topology for the scene.
In one embodiment of the system the printer prints the x,y bitmap for the interference hologram using ionic ink on one surface of a medium comprising an electrophoretic gel layer, and provides the z dimension for the topology by elecrophoresis of the ink into the gel of the medium. In another embodiment the printer prints the x,y bitmap for the interference hologram using magnetic ink on one surface of a medium comprising a porous layer, and provides the z dimension for the topology by magnetic migration of the of the ink into the gel of the medium.
In another aspect of the invention a topology printer for producing a white-light interference hologram is provided, comprising a print head adapted for depositing ionic ink in a bit-map pattern on a surface of a medium comprising an electrophoretic gel layer; and an electrode head disposed opposite the print head and spaced apart from the print head, creating a passage for the medium. The electrode head creates an electric field for each bit in the bit map pattern, the field controlled in magnitude and duration to migrate the ionic ink of each bit into the electrophoretic gel by a z-dimension, creating thereby the topology for the white-light interference hologram. In a preferred embodiment print head is adapted to deposit plural bits simultaneously in a fixed pattern, and the electrode head comprises a separate electrode for each bit, with the electrodes arranged in the same pattern as the fixed pattern of simultaneously-deposited bits. Also in an embodiment one or both of the gel and the ink are curable by radiated energy, and the printer further comprises a radiation head disposed to apply curing radiation immediately following migration of ink bits into the gel layer.
Another printer for producing a white-light interference hologram is provided, comprising a print head adapted for depositing magnetic ink in a bit-map pattern on a surface of a medium comprising a porous layer; and a magnetic head disposed opposite the print head and spaced apart from the print head, creating a passage for the medium. In this embodiment the magnetic head creates a magnetic field for each bit in the bit map pattern, the field controlled in magnitude and duration to migrate the magnetic ink of each bit into the porous layer by a z-dimension, creating thereby the topology for the white-light interference hologram.
In yet another embodiment a topology printer for producing a white-light interference hologram is provided, comprising a laser head adapted for producing openings in a print medium, the openings provided in a bit-map array according to two-dimensional x,y data for a white-light interference hologram, and each to a depth according to a z-dimension for each bit in the two-dimensional array; and a print head adapted for depositing ink over the openings provided by a the laser head, in a manner that the ink for each bit is migrated by capillary action into each opening in the bit map array, creating thereby the white-light interference hologram.
In other aspects several methods are taught for practicing the invention using the apparatus described and taught.
In yet another embodiment a digital camera for capturing information to create a white-light interference hologram of a scene is provided, comprising a first charge-coupled device (CCD) array for capturing a first bit-map file of the scene from a first vantage point; and a second CCD array spaced apart by a first spacing from the first CCD array, the second CCD array for capturing a second bit-map file of the scene from a second vantage point. The first spacing is adjustable and measurable by the camera to be stored with the first and second bit-mapped files.
Finally a medium for producing a white-light interference hologram is taught, the medium comprising a porous transmissive layer for accepting ink applied in a bit-mapped pattern; and a transparent electrophoretic gel layer adjacent the transmissive layer for providing a depth field for ink applied in the bit-mapped pattern.
With the apparatus and methods taught, interference holograms can, for the first time, be created by taking a picture with a digital camera, and printing the hologram from the captured picture data, transformed by algorithm, the printing being done on an apparatus much like an ink-jet printer. These and other aspects of the invention are taught below in enabling detail.